Phase I Dose-Escalation Study of JNJ-42756493, an Oral Pan-Fibroblast Growth Factor Receptor Inhibitor, in Patients With Advanced Solid Tumors.

PURPOSE: JNJ-42756493 is an orally administered pan-fibroblast growth factor receptor (FGFR) tyrosine kinase inhibitor. This first-in-human study evaluates the safety, pharmacokinetics, and pharmacodynamics and defines the recommended phase II dose (RP2D) of JNJ-42756493. PATIENTS AND METHODS: Eligible patients with advanced solid tumors received escalating doses of JNJ-42756493 from 0.5 to 12 mg administered continuously daily or JNJ-42756493 10 or 12 mg administered intermittently (7 days on/7 days off). RESULTS: Sixty-five patients were enrolled. The most common treatment-emergent adverse events included hyperphosphatemia (65%), asthenia (55%), dry mouth (45%), nail toxicity (35%), constipation (34%), decreased appetite (32%), and dysgeusia (31%). Twenty-seven patients (42%) experienced grade ≥ 3 treatment-emergent adverse events, and one dose-limiting toxicity of grade 3 ALT elevation was observed at 12 mg daily. Maximum-tolerated dose was not defined. Nine milligrams daily was considered as the initial RP2D; however, tolerability was improved with intermittent schedules, and 10 mg administered on a 7-days-on/7-days-off schedule was considered the final RP2D. Pharmacokinetics were linear, dose proportional, and predictable, with a half-life of 50 to 60 hours. Dose-dependent elevations in serum phosphate, a manifestation of pharmacodynamic effect, occurred in all patients starting at 4 mg daily. Among 23 response-evaluable patients with tumor FGFR pathway alterations, four confirmed responses and one unconfirmed partial response were observed in patients with glioblastoma and urothelial and endometrial cancer (all with FGFR2 or FGFR3 translocations); 16 patients had stable disease. CONCLUSION: JNJ-42756493 administered at 10 mg on a 7-days-on/7-days-off schedule achieved exposures at which clinical responses were observed, demonstrated pharmacodynamic biomarker activity, and had a manageable safety profile.

The human IL-17F/IL-17A heterodimeric cytokine signals through the IL-17RA/IL-17RC receptor complex.

IL-17A and IL-17F, produced by the Th17 CD4(+) T cell lineage, have been linked to a variety of inflammatory and autoimmune conditions. We recently reported that activated human CD4(+) T cells produce not only IL-17A and IL-17F homodimers but also an IL-17F/IL-17A heterodimeric cytokine. All three cytokines can induce chemokine secretion from bronchial epithelial cells, albeit with different potencies. In this study, we used small interfering RNA and Abs to IL-17RA and IL-17RC to demonstrate that heterodimeric IL-17F/IL-17A cytokine activity is dependent on the IL-17RA/IL-17RC receptor complex. Interestingly, surface plasmon resonance studies indicate that the three cytokines bind to IL-17RC with comparable affinities, whereas they bind to IL-17RA with different affinities. Thus, we evaluated the effect of the soluble receptors on cytokine activity and we find that soluble receptors exhibit preferential cytokine blockade. IL-17A activity is inhibited by IL-17RA, IL-17F is inhibited by IL-17RC, and a combination of soluble IL-17RA/IL-17RC receptors is required for inhibition of the IL-17F/IL-17A activity. Altogether, these results indicate that human IL-17F/IL-17A cytokine can bind and signal through the same receptor complex as human IL-17F and IL-17A. However, the distinct affinities of the receptor components for IL-17A, IL-17F, and IL-17F/IL-17A heterodimer can be exploited to differentially affect the activity of these cytokines.

Wnt/beta-catenin signaling is a normal physiological response to mechanical loading in bone.

A preliminary expression profiling analysis of osteoblasts derived from tibia explants of the high bone mass LRP5 G171V transgenic mice demonstrated increased expression of canonical Wnt pathway and Wnt/beta-catenin target genes compared with non-transgenic explant derived osteoblasts. Therefore, expression of Wnt/beta-catenin target genes were monitored after in vivo loading of the tibia of LRP5 G171V transgenic mice compared with non-transgenic mice. Loading resulted in the increased expression of Wnt pathway and Wnt/beta-catenin target genes including Wnt10B, SFRP1, cyclin D1, FzD2, WISP2, and connexin 43 in both genotypes; however, there was a further increased in transcriptional response with the LRP5 G171V transgenic mice. Similar increases in the expression of these genes (except cyclin D1) were observed when non-transgenic mice were pharmacologically treated with a canonical Wnt pathway activator, glycogen synthase kinase 3beta inhibitor and then subjected to load. These in vivo results were further corroborated by in vitro mechanical loading experiments in which MC3T3-E1 osteoblastic cells were subjected to 3400 microstrain alone for 5 h, which increased the expression of Wnt10B, SFRP1, cyclin D1, FzD2, WISP2, and connexin 43. Furthermore, when MC3T3-E1 cells were treated with either glycogen synthase kinase 3beta inhibitor or Wnt3A to activate Wnt signaling and then subjected to load, a synergistic up-regulation of these genes was observed compared with vehicle-treated cells. Collectively, the in vivo and in vitro mechanical loading results support that Wnt/beta-catenin signaling is a normal physiological response to load and that activation of the Wnt/beta-catenin pathway enhances the sensitivity of osteoblasts/osteocytes to mechanical loading.

From genome to phenome--RNAi library screening and hit characterization using signaling pathway analysis.

Comprehensive, high-throughput analysis of gene function using RNA interference (RNAi)-based screens is emerging as a significant step forward for preliminary drug-target identification. Until quite recently drug target identification depended heavily on the analysis of changes in gene expression, which in turn needed to be correlated with gene function. The promise of obtaining preliminary 'gene to phenotype' information using a single high-throughput platform is propelling major investment in this area by biotechnology and pharmaceutical companies. This review discusses recent developments in the use of RNAi library screens, and the various assay formats and techniques currently in use for data analysis downstream of such screens.

Exploring the sounds of silence: RNAi-mediated gene silencing for target identification and validation.

Drug development begins with the identification and early preclinical validation of novel biological targets, a process often called 'target identification and validation'. This process usually uses various approaches, such as observations from literature and findings from animal or clinical studies, together with cutting edge molecular techniques that include analyses of gene and protein expression, interaction and function. The publication of the human genome has increased research in gene and protein expression analysis that, in combination with RNA interference technology, promises the evaluation of novel functions for known genes, as well as hitherto unknown or unstudied genes with functions relevant to disease.

Novel roles of unphosphorylated STAT3 in oncogenesis and transcriptional regulation.

Signal transducer and activator of transcription 3 (STAT3) is phosphorylated on tyrosine residue 705 in response to growth factors or cytokines to form activated homodimers that drive gene expression. Because the stat3 promoter has a binding site for STAT3 dimers, the amount of STAT3 protein increases when STAT3 is activated (e.g., in response to interleukin 6). Unphosphorylated STAT1 is known to drive the expression of certain genes. To explore the possibility of a similar role for the induced expression of unphosphorylated STAT3, we overexpressed either Y705F STAT3, which can not be phosphorylated on residue 705, or wild-type STAT3 in normal human mammary epithelial cells or STAT3-null mouse cells. The levels of many mRNAs were affected strongly by high levels of either form of STAT3. Some genes whose expression was increased by overexpressed STAT3, but not by activated STAT3 dimers, encode well-known oncoproteins (e.g., MRAS and MET). In many tumors, STAT3 is activated constitutively, and thus the unphosphorylated form is likely to be expressed highly, driving oncogene expression by a novel mechanism. In addition, expression of the stat3 gene is increased strongly in response to interleukin 6, and the high levels of unphosphorylated STAT3 that result drive a substantial late phase of gene expression in response to this cytokine. Thus, unphosphorylated STAT3, which activates gene expression by a novel mechanism distinct from that used by STAT3 dimers, is very likely to be an important transcription factor both in cancer and in responses to cytokines.

NAK is recruited to the TNFR1 complex in a TNFalpha-dependent manner and mediates the production of RANTES: identification of endogenous TNFR-interacting proteins by a proteomic approach.

Tumor necrosis factor alpha (TNFalpha) is a proinflammatory cytokine with pleiotropic immunological and biological activities. TNFalpha signaling is triggered by the engagement of soluble TNFalpha to two types of cell surface receptors, TNFR1 and TNFR2. This recruits cytosolic proteins to the intracellular domains of the receptors and initiates signaling to downstream effectors. In this study, we used a proteomic approach to identify these cytosolic proteins from affinity-purified, endogenous TNFalpha.TNFR complexes in human myelomonocytic U937 cells. Seven proteins were identified, including TRADD, TRAP2, and TRAF2, which are three proteins known to be recruited to TNFalpha receptors. NAK, RasGAP3, TRCP1, and TRCP2 were also identified. We further showed that NAK is recruited to TNFR1 in a temporally regulated and TNFalpha-dependent manner and that it mediates the TNFalpha-induced production of the chemokine RANTES (regulated on activation normal T cell expressed and secreted). These data demonstrate that NAK is a component of the TNFalpha.TNFR1 signaling complex and confirm the physiological role of NAK in the TNFalpha-mediated response.

From differential gene expression to differential gene function and back.

Following the decoding of several plant and animal genomes, the identification of all corresponding transcripts and proteins and understanding how their expression corresponds to physiological and pathological states is the obvious next step. Nucleic acid quantification methods have become increasingly high-throughput and relatively low-cost, and moving ahead, combinations of technologies monitoring differential gene expression and those defining differential cellular function will yield maximum benefit in furthering biology and for drug target identification and validation.:

IRAK-dependent phosphorylation of Stat1 on serine 727 in response to interleukin-1 and effects on gene expression.

Interleukin-1 (IL-1) induces the phosphorylation of Stat1 on serine 727 but not on tyrosine 701. Analyses of mutant I1A cells, which lack the IL-1 receptor-associated kinase (IRAK), and of I1A cells reconstituted with deletion mutants of IRAK show that the IL-1-mediated phosphorylation of Stat1 on serine requires the IRAK protein but not its kinase activity and does not involve phosphatidylinositol-3'-kinase (PI3K) or the mitogen-activated protein (MAP) kinases p38 or ERK. IRAK and Stat1 interact in vivo, and this interaction is increased in response to IL-1, suggesting that IRAK may serve to recruit the as yet unknown IL-1-induced Stat1 serine kinase. Chemical inhibitors or dominant-negative forms of signaling components required to activate NF-kappa B, ATF, or AP-1 in response to IL-1 do not affect the phosphorylation of Stat1 on serine. IL-1 and tumor necrosis factor (TNF) enhance the serine phosphorylation of Stat1 that occurs in response to interferon-gamma (IFN-gamma) and potentiate IFN-gamma-mediated, Stat1-driven gene expression, thus contributing to the synergistic activities of these proinflammatory cytokines.

Resistance to interferons in melanoma cells does not correlate with the expression or activation of signal transducer and activator of transcription 1 (Stat1).

Defects in expression or activation signal transducer and activator of transcription-1 (Stat1) in response to interferon-alpha2 (IFN-alpha2) have been implicated as a mechanism for IFN resistance in melanoma cells. To further determine the significance of this observation, 17 melanoma cell lines sensitive or resistant to the antiproliferative effects of IFN-alpha2 and IFN-beta, as well as 30 melanoma patient samples, were analyzed for Stat1 levels by either Western blot analysis or immunohistochemistry. Although the expression level varied between samples, all the cell lines except one and all melanoma biopsy specimens expressed Stat1. IFN-stimulated levels of Stat1 and Stat2, which constitute the transcriptional activation complexes, such as, gamma activated factor (GAF) and IFN-stimulated gene factor 3 (ISGF3), for IFN-stimulated gene (ISG) induction were assessed in melanoma cell lines. Both IFN-alpha2 and INF-beta induced equivalent amounts of Stat1 and Stat2 proteins in cell lines, although compared with IFN-alpha2, IFN-beta had greater antiproliferative effects. No significant differences were observed in tyrosine or serine phosphorylation of Stat1 or the formation of GAF or ISGF3 complexes following IFN-alpha2 or IFN-beta treatment of IFN-resistant or IFN-sensitive cell lines. Comparable induction of two ISGs, ISG54 and IFN regulatory factor-1 (IRF-1), was observed in both sensitive WM9 and resistant A375 cells. Therefore, we report that defects in expression or activation of Stat1 or Stat2 were infrequent in melanoma cell lines and tumor samples and did not correlate with IFN resistance. Cellular resistance to IFNs likely results from defective quantitative or qualitative expression of specific ISGs.

Stat1-dependent, p53-independent expression of p21(waf1) modulates oxysterol-induced apoptosis.

7-Ketocholesterol (7kchol) is prominent in atherosclerotic lesions where apoptosis occurs. Using mouse fibroblasts lacking p53, p21(waf1), or Stat1, we found that optimal 7kchol-induced apoptosis requires p21(waf1) and Stat1 but not p53. Findings were analogous in a human cell system. Apoptosis was restored in Stat1-null human cells when wild-type Stat1 was restored. Phosphorylation of Stat1 on Ser(727) but not Tyr(701) was essential for optimum apoptosis. A neutralizing antibody against beta interferon (IFN-beta) blunted Ser(727) phosphorylation and apoptosis after 7kchol treatment; cells deficient in an IFN-beta receptor subunit exhibited blunted apoptosis. IFN-beta alone did not induce apoptosis; thus, 7kchol-induced release of IFN-beta was necessary but not sufficient for optimal apoptosis. In Stat1-null cells, expression of p21(waf1) was much less than in wild-type cells; introducing transient expression of p21(waf1) restored apoptosis. Stat1 and p21(waf1) were essential for downstream apoptotic events, including cytochrome c release from mitochondria and activation of caspases 9 and 3. Our data reveal key elements of the cellular pathway through which an important oxysterol induces apoptosis. Identification of the essential signaling events that may pertain in vivo could suggest targets for therapeutic intervention.

Isolation and characterization of a human STAT1 gene regulatory element. Inducibility by interferon (IFN) types I and II and role of IFN regulatory factor-1.

The transcription factor STAT1 plays a pivotal role in signal transduction of type I and II interferons (IFNs). STAT1 activation leads to changes in expression of key regulatory genes encoding caspases and cell cycle inhibitors. Deficient STAT1 expression in human cancer cells and virally mediated inhibition of STAT1 function have been associated with cellular resistance to IFNs and mycobacterial infection in humans. Thus, given the relative importance of STAT1, we isolated and characterized a human STAT1 intronic enhancer region displaying IFN-regulated activity. Functional analyses by transient expression identified a repressor region and type I and II IFN-inducible elements within the STAT1 enhancer sequence. A candidate IRF-E/GAS/IRF-E (IGI) sequence containing GAAANN nucleotide repeats was shown by gel shift assay to bind to IFN regulatory factor-1 (IRF-1), but not to IFN-stimulated gene factor-3 (ISGF-3) or STAT1-3. An additional larger IGI-binding complex containing IRF-1 was identified. Mutation of the GAAANN repeats within the IGI DNA element eliminated IRF-1 binding and the IFN-regulated activity of the STAT1 intronic enhancer region. Transfection of the IFN-resistant MM96 cell line to express increased levels of IRF-1 protein also elevated STAT1, STAT2, and p48/IRF-9 expression and enhanced cellular responsiveness to IFN-beta. Reciprocating regulation between IRF-1 and STAT1 genes and encoded proteins indicates that an intracellular amplifier circuit exists controlling cellular responsiveness to the IFNs.